Dog poop and urine may harm nature reserves, according to a new study

significant fertilization level

Researchers at Ghent University estimate that dog feces and urine add an average of 11 kilograms of nitrogen and 5 kilograms of phosphorus per hectare each year to a nature reserve near the Belgian city of Ghent

This estimate of the increase in nitrogen from a previously unrecorded source is especially significant compared to the total amount of nitrogen added by fossil fuel emissions and agriculture (5 to 25 kg per hectare) in most of Europe

Professor Pieter De Frenne from Ghent University, lead author of the study, said: "We were surprised by how high the nutrient input to dogs was

The researchers called on land managers, especially in low-nutrient ecosystems, to highlight the negative effects of dog fertilization to tourists, encouraging them to remove dog feces

Dogs and owners on a leash have a big impact on removing feces

In this experiment, the researchers calculated the amount of nutrients the dogs were adding to the environment by recording the number of dogs present in four nature reserves

When the researchers simulated a scenario where all dogs were kept on a leash (a legal requirement in all reserves), they found that doing so reduced fertilization rates in most reserves, but greatly improved small areas around trails fertilization rate

Professor De Frenne said: "With all dogs on a leash, we found that in concentrated areas around these roads, nutrient inputs of nitrogen and phosphorus exceeded legal limits for fertilization of agricultural land

The researchers found that in the dog-leash scenario, all owners picked up the dog's feces, which reduced nitrogen fertilization levels by 56 percent and phosphorus fertilized levels by 97 percent

Increased nutrients are a problem for nature reserves

Adding nutrients to nature reserves may sound beneficial as this promotes plant growth, however, this mostly occurs with a limited number of nutrient-requiring species that are more competitive than rarer specialists, reducing biodiversity

"In many nature reserves, the specific goal of management is to reduce soil nutrient levels in order to increase plant and animal biodiversity

Calculate nutrient levels

To estimate the amount of nutrients dogs add to the environment, the researchers first calculated the number of dogs per hectare per year by counting dogs in four nature reserves near the Belgian city of Ghent

While this method meant that the researchers could accurately count the number of dogs in the nature reserve, the estimates had to be based on the average number of dogs, the average amount of urine and feces, and the concentrations of nitrogen and phosphorus

The researchers said their data could be improved by recording the dog's breed, size, weight, and amount of urine and feces, such as by asking the owner